A model for the interaction of the melanocortin-1 (MC1) receptor with MSH peptide has been constructed. The model was built by homology modelling using bacteriorhodopsin as template. A cyclic analogue of MSH could be docked into a binding pocket located between transmembrane (TM) domains 2, 3 and 6 of the receptor. The most significant receptor to ligand interactions occur between D117 in TM3 of receptor with histidine in cyclic MSH-peptide, H260 in TM6 with glutamic in peptide and D121 in TM3 with arginine in peptide. The model finds support from earlier mutagenesis data.